The present invention is directed to an adaptor which permits a Chevrolet Corvette C5 or C6 rear end assembly to be used in a rebuild of an older Corvette, such as a C1, C2, or C3 generation model.
The Corvette has had six generations of vehicle design, typically known in the industry as C1 through C6, with the C1 being produced from 1953 to 1962, the C2 being produced from 1963 to 1967, the C3 being produced from 1968 to 1982, the C4 being produced from 1984 to 1996, the C5 being produced from 1997 to 2004, and the C6 being produced from 2005 to date.
Each generation has maintained a fundamental design in its body, suspension, drive train, and engines, with changes being introduced from model year to model year within a generation to meet pollution requirements and changes in gasoline chemistry, to introduce appearance features, or to change engine and transmission specifications for sales promotion purposes.
Through the years, the Corvette has become an American icon in the automotive industry. Attractive styling, sports car performance, and the use of fiberglass and plastic materials and exotic metals have attributed to a long standing desirability for older Corvette models among the public.
An industry now exits in which older Corvettes are rebuilt or remanufactured from the ground up, i.e., from the frame outward. These rebuilt Corvettes often sell privately or at auction for in excess of $150,000 depending upon the model. The rebuilding of an older Corvette becomes the building of a Corvette as new parts from frame to suspension, to brakes, to engine, to drive train are introduced. Of necessity, the body remains, in whole or in part, from the original factory production.
Through the various generations, changes have occurred in engines, drive trains, transmissions and suspensions. The C1 Corvette began with an inline six-cylinder engine, a two-speed automatic transmission, drum brakes and a solid rear axle with longitudinal leaf springs. A “small-block” (1955-1956) V8 engine and constant flow fuel injection was later introduced for the C1 Corvette for 1957-1961 in a 283 cu. in. engine.
The C2 Corvette started with independent rear suspension, and a larger small-block (327 cu in) V8 engine with optional electronic ignition. As the C2 model years progressed with even higher horsepower with the larger (327 cu. in.) V8 engines and introduced two big-block (396 cu in and 427 cu in) V8 engines with modified automatic and manual transmissions and changes in carburation. These C2 big-block Corvettes are one of the most desirable antique vehicles in the United States.
The C4 Corvette introduced a light-weight composite, transversely mounted, monoleaf front suspension that has been the standard for Corvettes ever since. A larger big-block (454 cu in) V8 engine with redesigned transmission was also introduced. The rear suspension remained with independent pivoting axels, leaf spring suspension similar to the design of the C2 Corvette. However, in later model years a cross-fire, throttle body injection engine was introduced, as well as plastic composite rear coil springs, thinner body panels, a catalytic converter, and an aluminum differential. More of the changes in model years addressed engine changes, engine modifications and transmission changes than changes in other portions of the vehicle.
As with earlier generations, the C4 Corvette introduced a change in body style and looks. It also introduced changes in engines, carburetion/fuel injection and transmissions, as well as a transverse composite leaf spring in the rear.
The C5 Corvette introduced major changes over the previous generations. Instead of a beam/rail type perimeter frame onto which the body was bolted, the C5 had a hydroformed perimeter frame integral with the body. The front and rear suspension assemblies which hold the engine, transmission, differential and suspension structure were joined by a center torque tube. The front suspension included alloy upper and lower control arms and steering knuckle, transverse monoleaf plastic composite spring, steel stabilizer bar, spindle offset and gas-pressurized shock absorbers positioned to operate within the cavities of the front wheels. The rear suspension was an independent 5-link design with toe-in and camber adjustment, alloy upper and lower control arms and knuckle, transverse monoleaf plastic composite spring, steel stabilizer bar and tie rods, tubular u-joint metal matrix composite drive shafts, and gas-pressurized shocks positioned to operate within the cavities of the rear wheels. The new geometry of the C5 rear suspension, including the new transverse leaf spring, offered greatly improved handling and lateral stability as well as providing an improved ride which reduced body rattles and squeaks.
The rear suspension short-long arm and transverse leaf spring independent suspension configuration of the C5 was carried over into the C6 Corvette. However, the geometry of the cradles, control arms, knuckles, dampers and stabilizer bars was redesigned. These changes, including adjustments in various dimensions, have produced ever-improved ride and handing, less road noise, and better body control under greater lateral acceleration.
Both the C5 and the C6 Corvette rear suspensions have height adjustments for raising or lowering the vehicle. It is well accepted in the marketplace that the C5 and C6 rear suspension designs are great improvements over the previous generations of Corvettes. Like the C4, the C5 and C6 suspensions continued with the leaf spring configuration, where the link arms permit the shock structure to extend into the interior space of the wheels.
Like the C5 Corvette, the present C6 Corvette has its transmission mounted to the rear differential. This feature was introduced in an effort to obtain a 50-50 weight distribution in the vehicles. However, for body clearance when adapting a C5 or C6 rear suspension to an older C1 through C3 Corvette, the transmission must be mounted to the engine.
While more and more Corvette enthusiasts are requesting C5 or C6 rear suspensions in their rebuilt older generation vehicles because of the better handling and ride, such crossover use is not possible without modification to the drive train and body.
Older Corvettes can have one-piece drive shafts connecting the transmission to the rear differential, with the transmission being mounted at the engine. In order to use a C5 or C6 rear suspension on the older Corvettes it is necessary to eliminate the rear mounted transmission and provide an adaptor between the drive shaft and the differential.
An object of the present invention is to provide an adaptor which mounts to an existing C5/C6 differential with the same sealing function as the C5/C6 transmission housing.
A second object is to provide an adaptor which will handle the power from a modern “crate” engine, an original specification engine and transmission when coupled to the end of the drive shaft.
A third is to provide an adaptor with a structure for more than one mounting configuration to accommodate different suspension height adjustments.
Another object is to provide an adaptor with a structure for coupling to the end of the drive shaft from a front-mounted transmission.
A further object is to provide an adaptor with sufficient lubrication to promote longevity of operation and reduce heat build-up.